1. Field of the Invention
The present invention relates to a process for preparing a powdery alkyl sulfate. More specifically, the present invention relates to a process for preparing a powdery alkyl sulfate which can be suitably used for laundry detergents, toothpaste additives, detergents and the like.
2. Discussion of the Related Art
As processes for preparing a powder or granulated product of an alkyl sulfate, there have been known a process comprising spray-drying aqueous slurry of an alkyl sulfate, the solid content of which is 60 to 80% by weight, by utilizing the minimum value of the viscosity of the aqueous slurry (Japanese Patent Laid-Open No. Sho 54-106428); a process comprising vacuum-thin-film drying aqueous slurry of an anionic surfactant such as an alkyl sulfate, the solid content of which is 60 to 80% by weight (Japanese Patent Laid-Open No. Hei 5-331496); a process for preparing a powder by controlling the water content of aqueous slurry of an anionic surfactant such as an alkyl sulfate to a very low level (Japanese Patent Laid-Open No. Hei 11-5999), and the like.
In those processes, while the solid content is adjusted to 60 to 80% by weight in order to lower the viscosity of the aqueous slurry of the alkyl sulfate, the viscosity of the aqueous slurry is remarkably high as compared to an aqueous solution of an alkyl sulfate. Therefore, there is a necessity in those processes to maintain the aqueous slurry at high temperatures in order to lower its viscosity and improve the operability of the aqueous slurry.
However, there are some defects in those processes that the aqueous slurry tends to be decomposed, and its pH is lowered when this aqueous slurry is kept at high temperatures, so that the quality before or after drying is deteriorated, thereby making it difficult to store the product for a long period of time.
An object of the present invention is to provide a process capable of stably preparing a powdery alkyl sulfate without deteriorating the quality of aqueous slurry of an alkyl sulfate and powder obtainable from the aqueous slurry.
The above and other objects of the present invention will be apparent from the following description.